Primary: Shoulder, Back, Neck (deltoideus, supra-/infraspinatus, erector spinae, trapezius)
Secondary: Arms, Abdominals (trizpes brachii, abdomini)

The extension with the outward rotation additionally trains besides of the shoulder, neck and back a part of the rotator cuff. This consists of multiple muscles, which fix the shoulder joint and allow miscellaneous motions.

The following figures illustrate the exercise Butterfly Reverse with Staggered Feet and Outward Rotation:

Schulter_Butterfly Reverse mit versetzten Füßen und Außenrotaion_1.jpg Schulter_Butterfly Reverse mit versetzten Füßen und Außenrotaion_2.jpg
Suspension Training Exercise For Shoulder Exercise

Starting Position

The upper body is leaned backwards while the back is straight. Both arms are stretched and placed in front of the chest. The palms point to each other. Both legs are placed in a light stepping stand; the posterior knee joint is flexed. The weight is shifted on the heels.

Final Position

The upper body is straight and both knee joints are stretched. The arms are placed sidewise of the body and are lightly flexed. The palms point upwards. Abdomen, back arm and shoulder muscles are tensed. The weight is distributed on both feet.

Movement 1

The upper body is straightened up by support of the shoulder and upper back muscles. The ischiocrural muscles can support the motion. The arms get turned parallel, until the palms point upwards.

Movement 2

The weight gets shifted back onto the heels. By moving the arms back in front of the chest, the upper body is slowly and controlled leaned back into the starting position.

Hint:

In the final position try to approach the shoulder blades as far as possible to each other, to stress the upper back muscles in an optimal way. Exercises with the rotator cuff should be done slowly and controlled.